Cathode Active Material Coating for Cobalt-Free Lithium Batteries
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Solution Overview
Problem
Current lithium battery cathode active materials face challenges in achieving high-rate characteristics and capacity, particularly due to the suppression of lithium deintercalation caused by interlayer movement of Mo6+ ions in materials like Li2MoO3, which lacks cobalt but suffers from instability and capacity issues.
Innovation Solution
A cathode composition incorporating a first lithium compound with an open-circuit voltage of 3V or greater and a second lithium compound with a metal oxide coating layer, where the second compound has an open-circuit voltage less than 3V, enhancing electrical characteristics by preventing discharge and deterioration through surface coating and optimizing lithium ion transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If Li2MoO3 is used as cathode active material to eliminate cobalt, then cost and toxicity are reduced, but lithium deintercalation is suppressed due to interlayer movement of Mo6+ ions
Solution Approach 1:
A coating layer comprising metal oxide is introduced as an intermediary between the Li2MoO3 cathode active material and the electrolyte. This coating layer prevents direct contact and harmful interactions while facilitating lithium ion transport, thereby resolving the contradiction between eliminating cobalt and maintaining lithium deintercalation capability
Solution Approach 2:
The cathode active material is transformed from a single material (Li2MoO3) to a composite structure consisting of Li2MoO3 core particles coated with metal oxide shell. This composite structure combines the cobalt-free advantage of Li2MoO3 with the protective and conductive properties of the metal oxide coating, simultaneously addressing cost reduction and performance maintenance
2Quantity of substance
If cathode active materials are designed for high capacity, then battery capacity increases, but high-rate characteristics deteriorate
Solution Approach 1:
The electrical conductivity and surface properties of the cathode active material are modified by changing the physical and chemical parameters of the coating layer, including metal oxide composition, coating thickness, and crystalline structure. These parameter changes enhance electron transport and lithium ion diffusion kinetics, improving high-rate characteristics while maintaining high capacity
Solution Approach 2:
The coating layer is applied selectively on the surface of the cathode active material particles, creating local quality differences between the core and surface regions. The core maintains high capacity characteristics while the surface coating enhances electrical conductivity and reaction kinetics, enabling both high capacity and improved high-rate performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves the cycle characteristics and capacity of lithium batteries by suppressing the deterioration of the anode active material, increasing the amount of transferable lithium ions, and maintaining stability, thereby extending battery life and performance.
Implementation Method 1
the second lithium compound has a metal oxide coating layer on a surface thereof
Implementation Method 2
deintercalation of lithium is suppressed due to interlayer movement of Mo6+ ions
Implementation Method 3
increasing the amount of transferable lithium ions
Data Source
AI summary
A cathode and a lithium battery including the cathode have improved electrical characteristics. The cathode includes a cathode active material composition including a conducting agent, a binder, and a cathode active material, wherein the cathode active material includes a first lithium compound and a second lithium compound, the first lithium compound having an open-circuit voltage greater than an open-circuit voltage of the second lithium compound, and wherein the second lithium compound includes a metal oxide coating layer.